1. Field of the Invention
The present invention relates to a semiconductor integrated circuit package, a printed circuit board, a semiconductor apparatus, and a power supply wiring structure that are suitable for use with high-speed signals.
2. Description of the Related Art
A band of frequencies currently used in semiconductor integrated circuits has already reached a GHz level and now got on track to exceed 10 GHz. In order to deal with such a high-speed signal, a power source is demanded of high-speed charge supply, and a ground (earth) is demanded of high-speed discharing when electric charge is unnecessary. A decoupling capacitor is disposed to serve such purposes, however, as indicated by the following formula (1), parasitic inductance L is present.
                    v        =                  L          ⁢                                    ⅆ              i                                      ⅆ              t                                                          (        1        )            
As a problem associated with the relationship represented by the formula (1), with a decrease of voltage corresponding to v, the higher the frequency becomes to effect high-speed variation, the more difficult the charge supply becomes.
Since it is difficult to decrease the parasitic inductance L in a practical manner, it is preferable that, as practiced in a multilayer board disclosed in Japanese Unexamined Patent Publications JP-A 8-181445 (1996), a decoupling capacitor is inserted in front of a switch circuit as a built-in component, for example. However, there is a limit to the degree of proximity of the decoupling capacitor to the switch circuit.
Moreover, in a greater-than-64-bit semiconductor integrated circuit, the supply of great current is desirable to effect simultaneous switching actions.
Variation in charge supply and discharge emerges in high-frequency component form, and power source and ground wirings extending to a decoupling capacitor provide the effect of a transmission line. Under the domination of the characteristic impedance exerted by the transmission line, current limitation is imposed in accordance with the Ohm's law as indicated by the following formula (2).I=Vdd/Z0  (2)
In order to avoid this current limitation, in general, so-called solid (plane) power supply and solid (plane) ground are disposed in a printed circuit board. However, it is well known in the field of high-frequency circuits that resonance occurs in the presence of the high-frequency component that will eventually cause “EMI” problems.